In a two-stroke or two-cycle internal combustion engine, a combustion chamber is defined between the head of the piston and the underside of a cylinder head in which a fuel/mixture is compressed and ignited by a spark from a spark plug triggered by an external triggering circuit or by an injection process or autogenously so that the compression heat effects the ignition. The combustion process within the combustion chamber drives the piston, in turn, and the process is repeated with discharge of the combustion products to an exhaust manifold in a well-known sequence of operations.
While a four-stroke or four-cycle engine operates with valves controlled by a timing chain or the like, the control of fluid flow, including the flow of the fuel/air mixture and exhaust gases or the air which is compressed within the combustion chamber is generally effected by the cooperation between the piston and slits forming the ports by means of which communication is effected between the intake manifold and the combustion chamber or between the exhaust manifold and the combustion chamber.
In prior art systems of this type, there is a tendency toward incomplete combustion so that, for example, in autogenous ignition engines, soot formation is observed. In this case and in the case of spark ignition engines, there may be incomplete combustion to the point that hydrocarbons can be released into the environment. By and large, therefore, two-stroke cycling engines require improvement with respect to the properties of the combustion. Printed German patent application D 14583 (published Dec. 20, 1956) discloses a piston-and-cylinder arrangement for a four-stroke engine using full injection and the principles of which, including its valving, are not directly applicable to a solution of the above-described problems of two-stroke engines.